The structural and motivational role of the unique lip‐flip movement in the gelada ( Theropithecus gelada ) facial display repertoire

Bibliographic Data

ID8317232
AuthorsStefanie P Lazow (0000-0003-1826-842X, Department of Anthropology Dartmouth College Hanover New Hampshire, corresponding author), Thore J Bergman (0000-0002-9615-5001, Department of Psychology University of Michigan Ann Arbor Michigan)
Year2020
Volume172
Issue2
Pages280-290
Publication date2020-06-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/ajpa.24031
PMID32100880
OpenAlexW3006947873
LanguageEN
Citations received3
References cited42

OBJECTIVES: Human language represents an extreme form of communicative complexity. Primate facial display complexity, which depends upon facial mobility, can be used as a model for the study of the evolution of communicative complexity. The gelada (Theropithecus gelada) is the only primate that can produce a lip-flip eversion. This study investigates the role of the lip-flip relative to the bared-teeth display to understand its role in generating communicative complexity. MATERIALS AND METHODS: We reviewed videos of gelada social interactions. We utilized the facial action coding system (FACS) to define structural component action units (AUs) of each display. We inferred display motivation from the behaviors of the display sender. RESULTS: The lip-flip was used only in combination with the essential AUs of the bared-teeth display, serving as an optional structural element added to produce a structural variant. Both the bared-teeth display with and without a lip-flip occurred most frequently with nonaggressive, submissive behaviors. The lip-flip was more frequently preceded by approach than the bared-teeth display, especially in males. The lip-flip was also present in the majority of structurally blended facial displays though the motivation of the non-lip-flip parent display often dominated. DISCUSSION: The lip-flip may potentially function as an indicator of benign intent after an approach or as an intensifying component of nonaggressive intent. Adaptations to increase facial mobility in geladas via facilitating the lip-flip may promote increased communicative complexity through increased conspicuousness and motivational signaling specification or intensification

Art · Biology · Cognitive psychology · Evolutionary biology · Function (biology) · Graphical display · Primate · Repertoire · Communication · Computer Science · Evolutionary Psychology and Human Behavior · Face Recognition and Perception · Neuroscience · Primate Behavior and Ecology · Psychology